A freestanding nitrogen-doped MXene/graphene cathode for high-performance Li-S batteries

Lithium-sulfur batteries (LSBs) take a leading stand in developing next-generation secondary batteries with an exceptionally high theoretical energy density. However, the insulating nature and undesirable shuttle effect still need to be solved to improve the electrochemical performance. Herein, a freestanding graphene supported N-doped Ti 3 C 2 T x MXene@S cathode is successfully synthesized via a straightforward no-slurry method. Due to its unique hierarchical microstructure, the MXene-C/S ternary hybrids with high capacity can effectively adsorb polysulfides and accelerate their conversion. Cooperatively, conductive rGO can ameliorate N-MXene nanosheet' restacking, making the lamellar N-Mxene coated sulfur particles disperse uniformly. The assembled Li-S battery with a freestanding Ti 3 C 2 T x @S/graphene electrode provides an initial capacity of 1342.6 mA h g −1 at 0.1C and only experiences a low capacity decay rate of 0.067% per cycle after. Even at a relatively high loading amount of 5 mg cm −2 , the battery can still yield a high specific capacity of 684.9 mA h g −1 at 0.2C, and a capacity retention of 89.3% after 200 cycles. Designing heteroatomic doped MXene/rGO freestanding cathode enhanced the chemical adsorption capability of the polysulfide.